The present invention relates to a small natural circulation pressurized water nuclear reactor of the calogenic or electrogenic type intended for local use. Such a reactor can be installed on an ocean drilling platform, or on a river or sheet of water, in an isolated region not having the electric power necessary for the operation of an industrial installation.
In view of these uses of a very particular type, such a reactor must be completely autonomous and transportable in a safe manner between a loading site, where its core is installed and its place of use. This reactor must also fulfil long term intrinsic safety conditions, preferably including the hypothesis of capsizing, because it has to be installed and transported at sea or on a river. Finally, the very local use of such a reactor makes it necessary for it to be constructed in a particularly simple manner, so as to reduce costs, increase reliability and simplify use thereof.
In the particular case of the nuclear propulsion of ships, small pressurized water nuclear reactors are already used. These reactors are generally derived by homothetic transformation from large pressurized water reactors. In particular, they still have pumps for circulating water from the primary circuit, as well as auxiliary circuits ensuring the extraction of the residual power on shut down and in the case of the ship capsizing. Thus, these reactors are too complex and costly to be used for the local production of electricity or heat according to the invention.
The present invention specifically relates to a pressurized water nuclear reactor of an original design and which is particularly simple, fulfilling all the imposed safety conditions, particularly in the case of capsizing, without having recourse to any auxiliary standby cooling circuit, whereby said reactor is also autopressurized and operates on a natural circulation basis, which makes it possible to eliminate the heating members of the pressurizer and the primary pumps indispensable in existing reactors.